Dr John Snow and Cholera Outbreak

One of the first examples of spatial analysis is from epidemiology. Dr John Snow investigated the cholera outbreak in 1854 in London. He postulated that cholera was transmitted through drinking water and not air. He noticed that the outbreak was centered on Broad Street public drinking pump.

Repeating the first spatial analysis with current tools

• We will be using ArcGIS Online to work with the map.
• Follow this link to start
• ESRI provides many different resources that will help you get started on spatial analysis:
  • Identify areas near commercial campgrounds where nassella tussock is a threat to campers
  • Map accident data regarding pedestrians and cyclists struck by vehicles
  • Collect and analyze the location and condition of drinking water fountains across Berkeley,CA
  • Map racial disparities in breast cancer mortality rates
  • Create homelessness risk map, explore spatial patteerns of various risk factors and compare characteristics among different homeless communities

There are many more projects…

• All other ArcGIS Pro projects

1. Map the variable you are researching

• choropleth map
• flow map
• cartogram
• dot density map
• isoline map
• …

• Which areas (counties) have the highest mortality?
  • Why is Chicago significant and Minneapolis is not?
  • What happens in Montana?
  • What happens along the coast?

Remember normal distributions?

Histograms

Scatter plot

Is there a correlation? (fit the line)

North Carolina Data

## Linking to GEOS 3.9.0, GDAL 3.2.1, PROJ 7.2.1

Reproject

Calculate distance

Distance Matrix

## Units: [m]
##           [,1]     [,2]      [,3]     [,4]
## [1,]      0.00 312185.0 128340.26 475622.6
## [2,] 440561.48 114939.9 590434.32      0.0
## [3,]  18943.99 352719.0  78755.87 517526.7

Overlay

Overlay Analysis

Overlaying in NC

##       [,1]  [,2]  [,3]  [,4]
## [1,]  TRUE  TRUE FALSE FALSE
## [2,]  TRUE  TRUE FALSE FALSE
## [3,] FALSE FALSE FALSE FALSE
## [4,] FALSE FALSE FALSE FALSE

Choropleth Map of County Areas

Choropleth Map of Births in North Carolina

More beautiful and custom maps

Centroids

## Warning in st_centroid.sf(nc): st_centroid assumes attributes are constant over
## geometries of x

Centroids + Proportional Symbols

## Warning in st_centroid.sf(nc): st_centroid assumes attributes are constant over
## geometries of x

## Warning in st_centroid.sf(nc): st_centroid assumes attributes are constant over
## geometries of x

Centroids + Proportional Symbols (Size) + Hue